Introduction

"Electroacoustic music is a generic term
describing music that uses electronically generated sound or sound
modified by electronic means, which may or may not be accompanied by
live voices or musical instruments, and which may be delivered live or
through speakers." [Smal93] Electroacoustic music is not a single,
straightforward musical genre; it is a collection of genres and styles
and has a wide variety of musical praxes [Helm96]. It is created with
all kinds of sound syntheses as well as sound transformations, so this
type of music has a variation in its reliance upon technological
mediation. A certain corpus of electroacoustic music is also called "acousmatic".
In a broader sense, acousmatic music may be said to be the music, which
is produced especially for electroacoustic music and presented through
loudspeakers thereby without visible sources of the constituent sounds.

Electroacoustic music is composed by means of a different technology,
now primarily computer-based, is used to access, generate, explore, edit
and configure the music files. Electroacoustic music is generated using
all kinds of sound sources like human and animal voices, traditional
instruments, audio oscillators, audio synthesizers and electro acoustic
instruments etc. Electroacoustic music is evolved from compositional
techniques and aesthetic approaches [Smal93]. Electroacoustic music
mainly takes advantage of recorded sounds that are electronically
altered to create sonic collages. The electroacoustic music is recorded
by using various types of analogue or digital media such as tape, hard
disk etc. and it helps the composers by new means for modifying recorded
sounds, including splicing (cutting the tape to create new
juxtapositions of sound), speed variation, and mixing (which allows two
or more different recordings to be played back at the same time).

Figure 1: Musical Analysis and RepresentationSystem (MARS)

As electroacoustic compositions - in
comparison to traditional western art music - share a set of unique
features and are therefore barely ascertainable by using historical
forms of musical notation [Aust96]. Some problems exist for the electroacoustic
music in transcription, visualization and description. Most
electroacoustic pieces contain spectral changes and other timbre
aspects. It is very difficult to find the source musical component for
certain sound events. Each musical component has varying frequency
ranges. Thus it is impossible to visualize certain aspects of this music
by using Oscillogram (amplitude versus time). Instead of using
oscillogram a more accurate representation (especially of the spectral
dimension) can be achieved by using sonograms (frequency versus time
with amplitude as colour scale. In order to overcome this obstacle, it
is required to annotate electroacoustic pieces by using some graphical
symbols instead of using notational symbols of traditional music.

Problems
in electroacoustic music visualization and
notation

Most electroacoustic music
contains spectral changes and other timbral aspects that are difficult
to notate using traditional musical notation. The sonogram has been
explored as a tool for understanding the sonic design of musical works.
It displays time on the x-axis and frequency on the y-axis. Pitches
occurring for some duration are shown as horizontal lines; bands of
frequencies correspond to bands across the sonogram while, gradual
timbral shifts appear as moving shapes across the display. Components,
which have more energy, appear as darker. The sonogram was considered to
have the pitch notation, phase analysis, and amplitude display (color
scale level) for an initial visualization of electroacoustic music.

Since electroacoustic music
is a collection of genres and styles that exceed conventional western
art music, it is - at least in the majority of cases - impossible to
notate its sounds traditionally [GaDe84]. Considering these
difficulties, a special kind of notation has to be developed. Thus there
is a need to highlight the sources for the purpose of documenting and
analyzing electroacoustic music. Electroacoustic music can be annotated
by using some graphical symbols, text, and bitmaps, and the annotated
information’s are stored in a community repository for sharing of
information and also for future reference. Electroacoustic music is
annotated in order to provide sharing, documenting of musical
information between musicologists or analysts.

The
composer's role in electroacoustic music

Electroacoustic music
radically altered the relation between the composer and the performing
musician, whereas the former absorbed the role of the latter. To create
sounds for electroacoustic music, the composer becomes the instrument
builder. In the electronic studio environment different aspects of
musical performance remain in the hands of the composer, like the
articulation of single sound events and rhythms. electroacoustic music
balancing and coordinating complex parts of the musical work may compare
the composer’s role compared to that of a conductor.

Visualizing
the Electroacoustic Music

Electroacoustic music
radically altered the relation between the composer and the performing
musician, whereas the former absorbed the role of the latter. To create
sounds for electroacoustic music, the composer becomes the instrument
builder. In the electronic studio environment different aspects of
musical performance remain in the hands of the composer, like the
articulation of single sound events and rhythms. electroacoustic music
balancing and coordinating complex parts of the musical work may compare
the composer’s role compared to that of a conductor.

Community Support

To support a community of
musicologists spread over several locations they need a tool with a
common repository to store the musical information. In the community
repository the musical information can be created, stored or edited by a
single user or a group of users. With this design issues there would be
an opportunity for the musicologists or analysts to work in an
environment where knowledge can be exchanged by means of musical data.
This pattern has the opportunity to share information and comments on
electroacoustic compositions.

Musical
Analysis and Representation System (MARS)

The
Musical Analysis and Representation System (MARS) is designed for the
purpose of documenting, analyzing, searching electroacoustic compositions
for the collaboration of researchers in a distributed setting being
connected via the Internet. In figure 1 the user interface can be
viewed. Here, the user can visualize the electroacoustic music in the
sonogram window for each different audio track. The user can freely
annotate the electroacoustic music files by using the predefined
annotation symbols, like straight line, bend line, circle, etc. In
addition, there are options to zoom, mute, solo etc for each different
audio track. By using the setting option, the user can freely change the
MARS setting like, changing the color for sonogram, etc. Even more, the
user can freely operate the multi track audio player by using the
buttons like, play, pause, stop, loop, etc.

Most
of the electroacoustic music compositions have multi-track audio files,
so there is a necessity to have an audio player with multi track
feature. This multi track audio player has to play eight ‘monophonic’
audio files through a special sound card. Due to a java bug (RFE
4558938) the multi channel sound card is triggered by C++ using the ASIO
Driver Interface package. The ASIO Driver package is used, since this
type of driver is internationally recognized. The native library for the
ASIO Driver Interface was written in C++ and integrated with the java
code by means of JNI (Java Native Interface) technology (ref. figure 2).
The ASIO Driver Interface package has a native interface for playing the
audio files through the multi channel sound card.

Figure 2: Eight
channel sound card control with with java

MARS
users may share their compositions. Hence, they can upload audio files
into the MARS system in order to initialize the system and also for
effective audio player usage. Therefore, the sonogram has to be computed
or downloaded from the FTP server. While the audio files are playing the
user can annotate the electroacoustic music, by using some graphical
symbols, text, bitmaps etc. The user has the option to loop the playback
for a specified annotation window, since using this option the user can
effectively annotate the musical information by hearing specifically to
the looped window. User can use the mute and solo button to hear music
for a specified audio track.
These
annotated information are stored into the XML database by using the
MPEG-7 standard. Annotated bitmaps files are stored into the FTP server,
and also these bitmaps files are retrieved from the FTP server during
the playback option (cf. figure 3).

Figure
3: Meta data management in
MARS

In
figure 4 we can view the user who is sitting in centre of a studio room,
where eight audio speakers are present. In the studio room the level of
acoustic and other issues are checked in order to maintain a good audio
effect for the electroacoustic music playback. The user can view the
sonogram for the different track and annotate the electroacoustic music
files. The annotated information can be simultaneously stored and
retrieved from the XML database. The user has the option to create new
annotation, delete or modifying the existing annotation. This allows
users to discuss compositions in a distributed setting and keeps a
discourse going on.